A lubricating oil composition for compressed-ignited engines for land-based vehicles often has to meet certain performance requirements as stipulated in specifications established by the industry and/or original equipment manufacturers (OEMs). In general, heavy duty engine oils have to provide adequate levels of oxidation and wear protection, sludge and deposit formation control, fuel economy benefits, compatibility with sealing materials, and other desirable physical and rheological characteristics that are essential for lubrication and serviceability, as determined by various standardized engine and bench tests. For example, a high frequency reciprocating rig wear test (HFRR) is used to determine the wear protection properties of a lubricant composition. Typically, wear protection can be provided by the addition of phosphorus to the fluid. However, environmental regulations and OEM specifications may restrict the maximum phosphorus levels in the lubricant. Hence, providing sufficient or improved wear performance without increasing the phosphorus concentration in the lubricant is desirable.
With regard to the foregoing, embodiments of the disclosure provide a compression-ignited engine lubricant composition and a method for reducing engine wear. The heavy duty engine lubricant composition includes                (a) a base oil;        (b) from about 0.04 to about 0.2 wt. % of oleamide based on a total weight of the lubricant composition;        (c) zinc dihydrocarbyl dithiophosphate; and        (d) a hydrocarbyl soluble dispersant.        
In a further embodiment, the hydrocarbyl soluble dispersant is a functionalized dispersant comprising a reaction product of (i) a hydrocarbyl-dicarboxylic acid or anhydride, (ii) a polyamine, (iii) a dicarboxyl-containing fused aromatic compound or anhydride thereof, and optionally, (iv) a non-aromatic dicarboxylic acid or anhydride, wherein the hydrocarbyl group of the hydrocarbyl-dicarboxylic acid or anhydride has a number average molecular weight of greater than 1800 Daltons as determined by gel permeation chromatography.
In a further embodiment, the functionalized dispersant comprises a reaction product of (i) a hydrocarbyl-dicarboxylic acid or anhydride, (ii) a polyamine, (iii) 1,8-naphtahlic anhydride, and optionally, (iv) a non-aromatic dicarboxylic acid or anhydride.
In a further embodiment, the functionalized dispersant comprises a reaction product of (i) a hydrocarbyl-dicarboxylic acid or anhydride, (ii) a polyamine, (iii) 1,8-naphtahlic anhydride, and optionally, (iv) a non-aromatic dicarboxylic acid or anhydride.
In another embodiment, the functionalized dispersant comprises a reaction product of (i) a polyisobutenyl succinic acid or anhydride, component, (ii) a polyamine, (iii) 1,8-naphthalic anhydride, and (iv) comprises maleic anhydride.
In another embodiment, the polyisobutenyl group of component (d) is derived from polyisobutylene having greater than 50 mole percent terminal vinylidene content.
The another embodiment, from about 0.25 to about 1.5 moles of component (iv) are reacted per mole of component (ii).
In a further embodiment, the lubricant composition further comprises (e) one or more hydrocarbyl substituted succinimide dispersants other than component (d), wherein the hydrocarbyl substituent of component (e) is derived from a polyolefin having a number average molecular weight ranging from about 950 to about 3000 Daltons as determined by gel permeation chromatography and wherein a weight ratio of (e) to (d) in the lubricant ranges from about 1:1 to about 1:10.
In another embodiment of the disclosure, zinc dihydrocarbyl dithiophosphate is derived from all primary alcohols; all secondary alcohols; a mixture of primary and secondary alcohols, or a mixture of zinc dihydrocarby dithiophosphates derived from primary and secondary alcohols, wherein the mole percent of primary alcohols in the mixture of alcohols or the mole percent hydrocarbyl groups in the mixture of zinc dithydrocarbyl dithiophosphates is at least 30 mole %.
In another embodiment of the disclosure, the zinc dihydrocarbyl dithiophosphate is derived from all primary alcohols or a mixture of primary and secondary alcohols.
In another embodiment, at least 60 mole % of hydrocarbyl groups in the zinc dihydrocarbyl dithiophosphate are derived from primary alcohols.
In a further embodiment, the lubricant comprises a mixture of zinc dihydrocarbyl dithiophosphates and wherein at least 30 mole % of hydrocarbyl groups in the mixture of zinc dihydrocarbyl dithiophosphates are derived from primary alcohols.
In a further embodiment, the lubricant contains from about 200 to about 1500 ppm by weight of phosphorus based on a total weight of the lubricant.
In a further embodiment, the zinc dithiophosphate delivers approximately 1100 ppm of phosphorus to the lubricant based on a total weight of the lubricant.
In another embodiment, the lubricant comprises from about 0.04 to about 0.2 wt. % of oleamide based on a total weight of the lubricant composition.
In one embodiment of the disclosure the lubricant comprises from about 1 to about 10 percent by weight of the dispersant based on a total weight of the lubricant composition.
In one embodiment of the disclosure the lubricant comprises from about 2 to about 7 percent by weight of the dispersant based on a total weight of the lubricant composition.
Another embodiment of the disclosure provides a method for reducing wear in a compression-ignited engine. The method includes lubricating the engine with a lubricant composition comprising:                (a) a base oil;        (b) oleamide;        (c) a zinc dithydrocarbyl dithiophosphate; and        (d) a functionalized dispersant comprising a reaction product of (i) a hydrocarbyl-dicarboxylic acid or anhydride, (ii) a polyamine, (iii) a dicarboxyl-containing fused aromatic compound or anhydride thereof, and optionally, (iv) a non-aromatic dicarboxylic acid or anhydride, wherein the hydrocarbyl group of the hydrocarbyl-dicarboxylic acid or anhydride has a number average molecular weight of greater than 1800 Daltons as determined by gel permeation chromatography.        
A further embodiment of the disclosure provides a method for reducing wear in a compression-ignited engine. The method includes (1) lubricating the engine with a lubricant containing (a) a base oil; (b) from about 0.04 to about 0.2 wt. % oleamide based on a total weight of the lubricant; (c) zinc dihydrocarbyl dithiophosphate in an amount sufficient to provide from about 200 to about 1100 ppm by weight of phosphorus based on a total weight of the lubricant; and (d) from about 2 to about 7 wt % of a hydrocarbyl soluble dispersant based on a total weight of the lubricant.
In another embodiment of the disclosure, the zinc dihydrocarbyl dithiophosphate is derived from all primary alcohols or a mixture of primary and secondary alcohols.
In another embodiment, at least 60 mole % of hydrocarbyl groups in the zinc dihydrocarbyl dithiophosphate are derived from primary alcohols
In another embodiment, the lubricant comprises from about 0.04 to about 0.2 wt. % of oleamide based on a total weight of the lubricant composition.
In one embodiment of the disclosure the lubricant comprises from about 1 to about 10 percent by weight of the dispersant based on a total weight of the lubricant composition.
In one embodiment of the disclosure the lubricant comprises from about 2 to about 7 percent by weight of the dispersant based on a total weight of the lubricant composition.
In another embodiment, a method of reducing wear in a compression-ignition engine comprises lubricating the engine with a lubricant comprising: (a) a base oil; (b) from about 0.04 to about 0.2 wt. % oleamide based on a total weight of the lubricant; (c) zinc dihydrocarbyl dithiophosphate in an amount sufficient to provide from about 200 to about 1100 ppm by weight of phosphorus based on a total weight of the lubricant; and (d) from about 2 to about 7 wt % of a hydrocarbyl soluble dispersant based on a total weight of the lubricant.
The following definitions of terms are provided in order to clarify the meanings of certain terms as used herein.
As used herein, the terms “oil composition,” “lubrication composition,” “lubricating oil composition,” “lubricating oil,” “lubricant composition,” “lubricating composition,” “fully formulated lubricant composition,” “lubricant,” “crankcase oil,” “crankcase lubricant,” “engine oil,” “engine lubricant,” “motor oil,” and “motor lubricant” are considered synonymous, fully interchangeable terminology referring to the finished lubrication product comprising a major amount of a base oil plus a minor amount of an additive composition.
As used herein, the terms “additive package,” “additive concentrate,” “additive composition,” “engine oil additive package,” “engine oil additive concentrate,” “crankcase additive package,” “crankcase additive concentrate,” “motor oil additive package,” “motor oil concentrate,” are considered synonymous, fully interchangeable terminology referring the portion of the lubricating composition excluding the major amount of base oil stock mixture. The additive package may or may not include the viscosity index improver or pour point depressant.
As used herein, the term “hydrocarbyl substituent” or “hydrocarbyl group” is used in its ordinary sense, which is well-known to those skilled in the art. Specifically, it refers to a group having a carbon atom directly attached to the remainder of the molecule and having predominantly hydrocarbon character. Examples of hydrocarbyl groups include:                (1) hydrocarbon substituents, that is, aliphatic (e.g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl) substituents, and aromatic-, aliphatic-, and alicyclic-substituted aromatic substituents, as well as cyclic substituents wherein the ring is completed through another portion of the molecule (e.g., two substituents together form an alicyclic moiety);        (2) substituted hydrocarbon substituents, that is, substituents containing non-hydrocarbon groups which, in the context of this invention, do not alter the predominantly hydrocarbon substituent (e.g., halo (especially chloro and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, amino, alkylamino, and sulfoxy);        (3) hetero substituents, that is, substituents which, while having a predominantly hydrocarbon character, in the context of this invention, contain other than carbon in a ring or chain otherwise composed of carbon atoms. Heteroatoms include sulfur, oxygen, nitrogen, and encompass substituents such as pyridyl, furyl, thienyl, and imidazolyl. In general, no more than two, for example, no more than one, non-hydrocarbon substituent will be present for every ten carbon atoms in the hydrocarbyl group; typically, there will be no non-hydrocarbon substituents in the hydrocarbyl group.        
As used herein, the term “percent by weight”, unless expressly stated otherwise, means the percentage the recited component represents to the weight of the entire composition.
The terms “soluble,” “oil-soluble,” or “dispersible” used herein may, but does not necessarily, indicate that the compounds or additives are soluble, dissolvable, miscible, or capable of being suspended in the oil in all proportions. The foregoing terms do mean, however, that they are, for instance, soluble, suspendable, dissolvable, or stably dispersible in oil to an extent sufficient to exert their intended effect in the environment in which the oil is employed. Moreover, the additional incorporation of other additives may also permit incorporation of higher levels of a particular additive, if desired.
The term “TBN” as employed herein is used to denote the Total Base Number in mg KOH/g as measured by the method of ASTM D2896 or ASTM D4739.
The term “alkyl” as employed herein refers to straight, branched, cyclic, and/or substituted saturated chain moieties of from about 1 to about 100 carbon atoms.
The term “alkenyl” as employed herein refers to straight, branched, cyclic, and/or substituted unsaturated chain moieties of from about 3 to about 10 carbon atoms.
The term “aryl” as employed herein refers to single and multi-ring aromatic compounds that may include alkyl, alkenyl, alkylaryl, amino, hydroxyl, alkoxy, halo substituents, and/or heteroatoms including, but not limited to, nitrogen, oxygen, and sulfur.
Additional details and advantages of the disclosure will be set forth in part in the description which follows, and/or may be learned by practice of the disclosure. The details and advantages of the disclosure may be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.